Loading data asynchronously is useful when there is huge data and has the advantage of not slowing the page down. It's recommended to fetch data asynchronously for better User Experience. This also allows you to control resolution of data from the server side based on the range selected. In the below example, try changing range using navigator to load data of new range asynchronously.
window.onload = function () {
var dataPoints1 = [], dataPoints2 = [];
var stockChart = new CanvasJS.StockChart("chartContainer",{
title:{
text:"Async Data Loading in StockChart"
},
rangeChanged: rangeChanged,
charts: [{
axisY2: {
prefix: "$"
},
data: [{
type: "candlestick",
yValueFormatString: "$#,###.##",
axisYType: "secondary",
dataPoints : dataPoints1
}]
}],
navigator: {
dynamicUpdate: false,
data: [{
dataPoints: dataPoints2
}],
slider: {
minimum: new Date(2015, 05, 01),
maximum: new Date(2019, 05, 01)
}
}
});
function addData(data) {
stockChart.options.charts[0].data[0].dataPoints = [];
for(var i = 0; i < data.length; i++){
stockChart.options.charts[0].data[0].dataPoints.push({x: new Date(data[i].dateTime*1000), y: [ Number(data[i].open), Number(data[i].high), Number(data[i].low), Number(data[i].close) ]});
}
stockChart.render();
}
function rangeChanged(e) {
var minimum = parseInt(e.minimum / 1000);
var maximum = parseInt(e.maximum / 1000);
var url = "https://canvasjs.com/services/data/datapoints-bitcoinusd.php?minimum="+minimum+"&maximum="+maximum;
$("#loader").css("display", "block");
$.getJSON(url, function(data) {
addData(data);
$("#loader").css("display", "none");
});
}
$("#loader").css("display", "block");
$.getJSON("https://canvasjs.com/services/data/datapoints-bitcoinusd.php", function(data) {
for(var i = 0; i < data.length; i++){
dataPoints1.push({x: new Date(data[i].dateTime*1000), y: [Number(data[i].open), Number(data[i].high), Number(data[i].low), Number(data[i].close)]});
dataPoints2.push({x: new Date(data[i].dateTime*1000), y: Number(data[i].close)});
}
$("#loader").css("display", "none");
stockChart.render();
});
}